Heat shields in vehicular applications are used to protect electronic packages, sensors, wiring, and other heat-sensitive systems from the hot components of the vehicle that operate at high temperatures and radiate substantial amounts of heat. A non-limiting list of such components includes the turbo charger, the exhaust manifold, the exhaust piping, the catalytic converter, and the like. The hot components can often operate at temperatures above 600° C., and may even reach 800° C. at certain locations, and are generally located in the engine compartment where ventilation is limited or under the vehicle where the heat-sensitive systems cannot be relocated further away from the heat source.
One conventional heat shield for such applications is formed from two relatively-thick metallic sheets, or sheet metal layers, that have been pressed or stamped into a desired three-dimensional shape and coupled together around their peripheral edges to form a substantially rigid hollow shell body. The shape of the shell body may be contoured to fit within the limited and often-narrow space that is available within the vehicle between the hot component and the protected device or sensor. In addition, the two metallic sheets that form the shell body are generally separated by a thin core layer of a flexible insulating fabric that serves to prevent the interior surfaces of the sheet metal layers from contacting or rubbing against each other. The outer surface of the metallic sheet layer closest to the heat source is often configured to reflect radiated heat away from the heat shield, while the core layer of insulating fabric blocks the path of heat conduction between the two sheet metal layers. The heat shield also generally includes fastening provisions, such as bolt holes or clips, for mounting the heat shield to the frame or structure of a vehicle.
In addition to providing a thermal barrier for protecting the heat-sensitive systems and devices located near the hot components, vehicular heat shields are also built to withstand high vibration levels. Such vibration levels can be generated by the various sources of vibration produced within a vehicle, including the internal combustion engine, transmission, compressors, pumps, cooling fans, the rotating belts and sheaves that power the various auxiliary vehicle systems, as well as any road-induced vehicular vibrations transmitted through the tires and the suspension. To avoid structural failure from high-cycle fatigue, the metallic sheets or sheet metal layers are often designed with robust, relatively thick walls and stiffening structures or embossments that reduce the heat shield's natural response to vibration. Unfortunately, this also increases the weight of the device, even when the metal layers are fabricated from aluminum alloy. When added together, the combined weight of all the components of the heat shields can generally result in a significant weight penalty for the vehicle.
Consequently, a need exists for thermal or heat shields for vehicles that can provide suitable thermal protection for heat-sensitive systems while maintaining their structural integrity, and that also weigh less than existing heat shields. It is toward such a lightweight thermal shield that the present disclosure is directed.